Cyan mixtures for dye transfer

ABSTRACT

Cyan thermal transfer dye mixtures comprise at least one anthraquinone dye whose absorption maximum is at a wavelength of from 600 to 750 nm and also at least one triazolopyridine, pyridone, 1-amidopyrid-2,6-dione, heterocyclic pyridone and/or halogenated quinolone dye.

The present invention relates to novel dye mixtures comprising at leastone anthraquinone dye whose absorption maximum is at a wavelength offrom 600 to 750 nm and also at least one dye of the formula I, II, III,IV and/or V ##STR1## where L¹ is C₁ -C₂₀ -alkyl, which may besubstituted and may be interrupted by from 1 to 4 oxygen atoms in etherfunction, substituted or unsubstituted phenyl or hydroxyl,

L² is a 5- or 6-membered carbocyclic or heterocyclic radical,

L³ is cyano, carbamoyl, carboxyl or C₁ -C₄ -alkoxy-carbonyl,

L⁴ is oxygen or a radical of the formula ##STR2## where Q¹ is in eachcase C₁ -C₈ -alkyl, which may be interrupted by 1 or 2 oxygen atoms inether function,

L⁵ is hydrogen or C₁ -C₄ -alkyl,

L⁶ and L⁷ are identical or different and each is independently of theother hydrogen, substituted or unsubstituted C₁ -C₁₂ -alkyl, C₅ -C₇-cycloalkyl, substituted or unsubstituted phenyl, substituted orunsubstituted pyridyl, substituted or unsubstituted C₁ -C₁₂ -alkanoyl,C₁ -C₁₂ -alkoxycarbonyl, substituted or unsubstituted C₁ -C₁₂-alkylsulfonyl, C₅ -C₇ -cycloalkylsulfonyl, substituted or unsubstitutedphenylsulfonyl, substituted or unsubstituted pyridylsulfonyl,substituted or unsubstituted benzoyl, pyridylcarbonyl orthienylcarbonyl, or together with the nitrogen atom joining themtogether are unsubstituted or C₁ -C₄ -alkyl-substituted succinimido,unsubstituted or C₁ -C₄ -alkyl-substituted phthalimido or a five- orsix-membered saturated heterocyclic radical, which may contain furtherhetero atoms,

Y is cyano or a radical of the formula CO--Q², CO--OQ² or CO--NHQ²,where Q² is hydrogen, C₁ -C₈ -alkyl, which may be substituted and may beinterrupted by 1 or 2 oxygen atoms in ether function, C₅ -C₇-cycloalkyl, phenyl or tolyl,

L⁸ is hydrogen, fluorine, chlorine, methyl or a radical of the formula--NH--CO--A¹, --NH--CO--OA¹, --NH--CO--NA¹ A², --NH--CS--OA¹,--NH--CS--NA¹ A², --NH--CO--A³, --NH--SO₂ --A¹, --NH--SO₂ --A³ or--NH--SO₂ --NA¹ A², where

A¹ and A² are identical or different and each is independently of theother C₁ -C₈ -alkyl, which may be substituted and may be interrupted by1 or 2 oxygen atoms in ether function, C₅ -C₇ -cycloalkyl, phenyl ortolyl, or else --NA¹ A² is amino, and

A³ is a five- or six-membered aromatic heterocyclic radical, which maybe benzofused and contain one or more hetero atoms selected from thegroup consisting of nitrogen, oxygen and sulfur,

L⁹ is hydrogen, fluorine or chlorine, or L⁸ and L⁹ together with thecarbon atoms to which they are attached are a five- or six-memberedaromatic carbocyclic or heterocyclic ring, L¹⁰ is the abovementionedradical A³ or a radical of the formula --CO--OA¹, --CO--NH--A¹,--CO--NH--CO--A¹, --CO--NH--CO--A³, --CO--NH--SO₂ --A³, --NH--CO--A¹,--NH--CO--OA¹, --NH--CO--NA¹ A², --NH--CS--OA¹, --NH--CS--NA¹ A²,--NH--CO--A³, --NH--SO₂ --A¹, --NH--SO₂ --A³ or --NH--SO₂ --NA¹ A²,where A¹, A² and A³ are each as defined above,

L¹¹ is fluorine, chlorine or bromine,

L¹² is hydrogen or C₁ -C₄ -alkyl, and

L¹³ is hydrogen, fluorine, chlorine or bromine,

and also to a process for the thermal transfer thereof.

In the thermal transfer printing process, a transfer sheet, whichcontains a thermally transferable dye in one or more binders with orwithout suitable assistants on a substrate, is heated from the back withan energy source, for example a thermal head or a laser, in the form ofshort heating pulses (duration: fractions of a second), causing the dyeto migrate out of the transfer sheet and diffuse into the surfacecoating of a receiving medium. The essential advantage of this processis that the amount of dye to be transferred, and hence the colorgradation, is readily controlled by controlling the energy to be emittedby the energy source.

In general, color recording involves the use of the three subtractiveprimaries yellow, magenta and cyan (with or without black).

It is known to carry out the thermal transfer printing process withindividual dyes or else with mixtures of dyes. However, it has beenfound that the dyes that are employed still have application defects.

It is an object of the present invention to provide novel dye mixturesin the cyan region that shall be advantageous for thermal transfer.

We have found that this object is achieved by the dye mixtures definedat the beginning.

One component of the novel dye mixtures comprises anthraquinone dyeswhose absorption maximum is at a wavelength of from 600 to 750 nm, inparticular at from to 680 nm.

Emphasis is here given to anthraquinone dyes of the formula VI, VII orVIII ##STR3## where a is 0 or 1,

R¹, R² and R³ are identical or different and each is independently ofthe others hydrogen, alkyl, alkoxyalkyl, alkanoyloxyalkyl,alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, each of which may have upto 20 carbon atoms and be phenyl-, C₁ -C₄ -alkylphenyl-, C₁ -C₄-alkoxyphenyl-, halophenyl-, benzyloxy-, C₁ -C₄ -alkylbenzyloxy-, C₁ -C₄-alkoxybenzyloxy-, halobenzyloxy-, halogen-, hydroxyl- orcyano-substituted, unsubstituted or C₁ -C₁₅ -alkyl-, alkoxy-, halogen-or benzyloxy-substituted phenyl, unsubstituted or C₁ -C₁₅ -alkyl-, C₁-C₁₅ -alkoxy-, halogen- or benzyloxy-substituted cyclohexyl or a radicalof the formula

    [--E--O].sub.m --R.sup.5,

where

E is C₂ -C₆ -alkylene,

m is 1, 2, 3, 4, 5 or 6, and

R⁵ is C₁ -C₄ -alkyl or unsubstituted or C₁ -C₄ -alkyl-or C₁ -C₄-alkoxy-substituted phenyl, and

R⁴ is hydrogen or cyano,

with the proviso that R² is hydrogen only when a is 0.

L² can be derived for example from components of the benzene, indole,quinoline, aminonaphthalene, aminothiazole or aminothiophene series.

Emphasis is given to dye mixtures comprising at least one dye of theformula I, II, III, IV and/or V where L² is a radical of the formula##STR4## where n is 0 or 1,

Z¹ is hydrogen, C₁ -C₈ -alkyl, which may be interrupted by 1 or 2 oxygenatoms in ether function, methoxy, ethoxy, C₁ -C₄ -alkylsulfonylamino,mono- or di(C₁ -C₄ -alkyl) aminosulfonylamino, or the radical --NHCOZ⁷or --NHCO₂ Z⁷, where Z⁷ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, whichmay be interrupted by one or two oxygen atoms in ether function,

Z² is hydrogen, methyl, methoxy or ethoxy,

Z³ and Z⁴ are identical or different and each is independently of theother hydrogen, C₁ -C₈ -alkyl, which may be substituted and may beinterrupted by one or two oxygen atoms in ether function, C₃ -C₄-alkenyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl, or together with thenitrogen atom joining them together are a five- or six-memberedsaturated heterocyclic radical, which may contain further hetero atoms,

Z⁵ is halogen or substituted or unsubstituted phenyl, and

Z⁶ is hydrogen, halogen, C₁ -C₈ -alkyl, substituted or unsubstitutedphenyl, substituted or unsubstituted benzyl, cyclohexyl, thienyl,hydroxyl or mono(C₁ -C₈ -alkyl) amino, and

L⁵ is as defined above.

Any alkyl, alkylene or alkenyl appearing in the abovementioned formulaecan be not only straight-chain but also branched.

Any substituted alkyl appearing in the above-mentioned formulae may haveas substituents for example, unless otherwise stated, cyano, phenyl,tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄-alkylaminocarbonyloxy or a C₁ -C₄ -alkoxycarbonyloxy in which thealkoxy group may be substituted by phenyl or C₁ -C₄ -alkoxy, Anysubstituted phenyl or pyridyl appearing in the abovementioned formulaemay have as substituents for example halogen, C₁ -C₄ -alkyl or C₁ -C₄-alkoxy.

E is for example ethylene, 1,2- or 1,3-propylene, 1,2-, 1,3-, 1,4- or2,3-butylene, pentamethylene, hexamethylene or 2-methylpentamethylene.

R¹ R², R³, R⁵, Z¹, L¹, L⁵, L⁶, L⁷, L¹², A¹, A², Q¹, Q², Z¹, Z³, Z⁴, Z⁶and Z⁷ are each for example methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl or tert-butyl.

R¹, R², R³, L¹, L⁶, L⁷, A¹, A², Q¹ Q² Z¹, Z³, Z⁴, Z⁶ and Z⁷ may eachalso be for example pentyl, isopentyl, neopentyl, tert-pentyl, hexyl,2-methylpentyl, heptyl, octyl, 2-ethylhexyl or isooctyl.

R¹, R², R³, L¹, L⁶ and L⁷ may each also be for example nonyl, isononyl,decyl, isodecyl, undecyl or dodecyl.

R¹, R², R³ and L¹ may each also be for example tridecyl, isotridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl oreicosyl. (The designations isooctyl, isononyl, isodecyl and isotridecylare trivial names derived from the alcohols obtained by the oxo process(cf. Ullmanns Enzyklopadie der technischen Chemie, 4th edition, volume7, pages 215 to 217, and volume 11, pages 435 and 436).).

R¹, R², R³, A¹, A², Q², L¹, Z¹ and Z⁷ may each also be for example2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2- or3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or3-butoxypropyl, 2- or 4-methoxybutyl, 2- or 4-ethoxybutyl or 2- or4-butoxybutyl.

L¹, R¹, R², R³, A¹, A², Q² and Z¹ may each also be for example3,6-dioxaheptyl, 3,6-dioxaoctyl, 4,8-dioxanonyl, 3,7-dioxaoctyl,3,7-dioxanonyl, 4,7-dioxaoctyl, 4,7-dioxanonyl or 4,8-dioxadecyl.

R¹, R², R³ and L¹ may each also be for example 3,6,9-trioxadecyl,3,6,9-trioxaundecyl, 3,6,9,12-tetraoxatridecyl,3,6,9,12-tetraoxatetradecyl, 2-methoxycarbonylethyl, benzyl, 1- or2-phenylethyl, 3-benzyloxypropyl or 2-, 3- or 4-chlorophenyl.

L³ may be for example methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, orsec-butoxycarbonyl

R¹, R², R³, L¹ and Z⁶ may each also be for example 2-, 3- or 4-methylphenyl, 2-, 3- or 4-ethylphenyl, 2-, 3- or 4-propylphenyl, 2-, 3-or 4-isopropylphenyl, 2-, 3- or 4-butylphenyl, 2,4-dimethylphenyl, 2-,3- or 4-methoxyphenyl, 2-, 3- or 4-ethoxyphenyl, 2-, 3- or4-isobutoxyphenyl or 2,4-dimethoxyphenyl.

L⁶ and L⁷ may each also be for example phenyl, 2-, 3- or 4-methylphenyl,2-, 3- or 4-methoxyphenyl, pyridyl, 2-, 3- or 4-methylpyridyl, 2-, 3- or4-methoxypyridyl, formyl, acetyl, propionyl, butyryl, isobutyryl,pentanoyl, hexanoyl, heptanoyl, octanoyl, 2-ethylhexanoyl,methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl,butoxycarbonyl, methylsulfonyl, ethylsulfonyl, propylsulfonyl,isopropylsulfonyl, butylsulfonyl, cyclopentylsulfonyl,cyclohexylsulfonyl, cycloheptylsulfonyl, phenylsulfonyl, tolylsulfonyl,pyridylsulfonyl, benzoyl, 2-, 3- or 4-methylbenzoyl, 2-, 3- or4-methoxybenzoyl, thien-2-ylcarbonyl or thien-3-ylcarbonyl.

R¹, R², R³, Q², L⁶, Z³ and Z⁴ may each also be for example 2-cyanoethyl,2- or 3-cyanopropyl, 2-acetyloxyethyl, 2- or 3-acetyloxypropyl,2-isobutyryloxyethyl, 2- or 3-isobutyryloxypropyl,2-methoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl,2-ethoxycarbonylethyl, 2- or 3-ethoxycarbonylpropyl,2-methoxycarbonyloxyethyl, 2- or 3-methoxycarbonyloxypropyl,2-ethoxycarbonyloxyethyl, 2- or 3-ethoxycarbonyloxypropyl,2-butoxycarbonyloxyethyl, 2- or 3-butoxycarbonyloxypropyl,2-(2-phenylethoxycarbonyloxy)ethyl, 2- or3-(2-phenylethoxycarbonyloxy)propyl, 2-(2-ethoxyethoxycarbonyloxy)ethylor 2- or 3-(2-ethoxyethoxycarbonyloxy)propyl.

Q², L⁶, L⁷, Z³ and Z⁴ may each also be for example benzyl,2-methylbenzyl, 1- or 2-phenylethyl, cyclopentyl, cyclohexyl,cycloheptyl or 2-, 3- or 4-methylphenyl.

Z¹ is for example methylsulfonylamino, ethylsulfonylamino,propylsulfonylamino, isopropylsulfonylamino, butylsulfonylamino, mono-or dimethylaminosulfonylamino, mono- or diethylaminosulfonylamino, mono-or dipropylaminosulfonylamino, mono- or diisopropylaminosulfonylamino,mono- or dibutylaminosulfonylamino or(N-methyl-N-ethylaminosulfonyl)amino.

Z⁶ may also be for example, like Z⁵⁰ fluorine chlorine or bromine.

Z⁶ may also be for example phenyl, 2-methylphenyl, 2,4-dimethylphenyl,2-methoxyphenyl, 2,4-dimethoxyphenyl, benzyl, 2-methylbenzyl,2,4-dimethylbenzyl, 2-methoxybenzyl, 2,4-dimethoxybenzyl, methylamino,ethylamino, propylamino, isopropylamino, butylamino, pentylamino,hexylamino, heptylamino, octylamino or 2-ethylhexylamino.

Z³ and Z⁴ may each also be for example allyl or methallyl.

L⁶ combined with L⁷ or Z³ with Z⁴ to form together with the nitrogenatom joining them together a five- or six-membered saturatedheterocyclic radical, which may have further hetero atoms, can be forexample pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl or N-(C₁ -C₄-alkyl)piperazinyl.

L⁶, L⁷, A¹ and A² may each also be for example cyclopentyl, cyclohexylor cycloheptyl.

A³ is derived from a five- or six-membered aromatic heterocyclic radicalwhich may be benzofused and have one or more hetero atoms selected fromthe group consisting of nitrogen, oxygen and sulfur.

Examples of suitable heterocyclic structures with or withoutsubstituents from which A³ can be derived are pyrrole, furan, thiophene,pyrazole, imidazole, oxazole, isoxazole, thiazole, isothiazole,1,2,4-triazole, 1,2,4-oxadiazole, 1,3,4-oxadiazole, 1,2,4-thiadiazole,1,3,4-thiadiazole, pyridine, pyridazine, pyrimidine or pyrazine.

Emphasis is here given to heterocycles of the pyrrole, thiophene,isoxazole, pyridine or pyridazine series.

Suitable A³ --CO or A³ --SO₂ radicals are in particular those five- orsix-membered aromatic heterocyclic radicals derived from the followingheterocyclic carboxylic acids A³ --COOH or sulfonic acids A³ --SO₃ H:##STR5## where M is in each case C₁ -C₄ -alkyl.

Preferred mixture components are dyes of the formula I or II where L³ iscyano.

Preferred mixture components further include dyes of the formula I or IIwhere L² is derived from a component of the benzene, indole, quinoline,aminonaphthalene, aminothiazole or aminothiophene series.

Preferred mixture components further include dyes of the formula I or IIwhere L¹ is C₁ -C₁₂ -alkyl, which may be substituted by C₁ -C₆-alkanoyloxy, by C₁ -C₈ -alkoxycarbonyl, whose alkyl chain may beinterrupted by 1 or 2 oxygen atoms in ether function, by phenyl or by C₁-C₄ -alkylphenyl and may be interrupted by 1 or 2 oxygen atoms in etherfunction.

Particularly preferred mixture components are dyes of the formula I orII where L¹ is alkyl, alkoxyalkyl, alkanoyloxyalkyl oralkoxycarbonyloxyalkyl, which may each have up to 12 carbon atoms,unsubstituted or methyl-substituted benzyl or unsubstituted ormethyl-substituted phenyl.

Particularly preferred mixture components further include dyes of theformula I or II where L² is a radical. of the abovementioned formulaIXa, IXc, IXl, IXm, IXn or IXo.

Preference for use as mixture components is given to dyes of the formulaIII where L² is a radical of the formula IXa, IXc, IXl, IXm, IXn, IXo orIXp, of which a radical IXc or IXl is particularly suitable.

Particular emphasis for use as mixture components is given to dyes ofthe formula IIIa ##STR6## where B¹ and B² are each independently of theother hydrogen, C₁ -C₈ -alkyl, phenyl, tolyl, C₁ -C₈ -alkylcarbonyl, C₁-C₈ -alkylsulfonyl, phenylsulfonyl, tolylsulfonyl, pyridylsulfonyl,benzoyl, methylbenzoyl, pyridylcarbonyl or thienylcarbonyl,

B³ is hydrogen, methyl, methoxy or the radical --NHCOZ⁷ or --NHCO₂ Z⁷where Z⁷ is phenyl, benzyl, tolyl or C.sub. -C⁸ -alkyl, which may beinterrupted by one or two oxygen atoms in ether function,

B⁴ and B⁵ are each independently of the other hydrogen, C₁ -C₈ -alkyl,2-cyanoethyl, benzyl, C₁ -C₄ -alkanoyloxy-C₂ -C₄ -alkyl, C₁ -C₄-alkoxycarbonyl-C₁ -C₄ -alkyl or C₁ -C₄ -alkoxycarbonyloxy-C₂ -C₄ -alkyland

B⁶ is hydrogen or methyl.

Particular emphasis for use as mixture components is also given to dyesof the formula IIIb ##STR7## where B⁷ is C₁ -C₆ -alkyl, phenyl, tolyl,anisidyl, benzyl, cyclohexyl or thienyl and B¹, B², B⁴, B⁵ and B⁶ areeach as defined under the formula IIIa.

Very particular emphasis is given to dyes of the formula IIIa where B¹and B² are each independently of the other C₁ -C₈ -alkylcarbonyl,benzoyl, methylbenzoyl or thienylcarbonyl.

Preference for use as mixture components is further given to dyes of theformula IV where

L⁸ is hydrogen, chlorine or methyl and

L⁹ is hydrogen or chlorine.

Particular preference for use as mixture components is further given topyridone dyes of the formula IV where L² is a radical of the formulaIXa, IXc, IXe, IXf, IXg, IXj, IXl, IXm, IXn or IXo, particular emphasisbeing given to a radical of the formula IXa or IXc.

Particularly suitable mixture components are pyridone dyes of theformula IVa ##STR8## where L⁸ is hydrogen, chlorine or methyl,

L⁹ is hydrogen or chlorine,

L¹⁰ is a radical of the formula --CO--NH--A¹, --NH--CO--A¹,--NH--CO--OA¹ or --NH--CO--NA¹ A², where A¹ and A² are eachindependently of the other C₁ -C₈ -alkyl, 2-cyanoethyl, benzyl, C₁ -C₄-alkanoyloxy-C₂ -C₄ -alkyl, C₁ -C₄ -alkoxycarbonyl-C₁ -C₄ -alkyl, C₁ -C₄-alkoxycarbonyloxy-C₂ -C₄ -alkyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl,or else --NA¹ A² is amino,

Z¹ is hydrogen, methyl, methoxy or the radical --NHCOZ⁷ or --NHCO₂ Z⁷,where Z⁷ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which may beinterrupted by 1 oxygen atom in ether function,

Z² is hydrogen, and

Z³ and Z⁴ are each independently of the other hydrogen, C₁ -C₈ -alkyl,2-cyanoethyl, benzyl, C₁ -C₄ -alkanoyloxy-C₂ -C₄ -alkyl, C₁ -C₄-alkoxycarbonyl-C₁ -C₄ -alkyl or C₁ -C₄ -alkoxycarbonyloxy-C₂ -C₄-alkyl.

Particularly suitable mixture components also include pyridone dyes ofthe formula IVb ##STR9## where L⁸ is hydrogen, chlorine or methyl,

L⁹ is hydrogen or chlorine,

L¹⁰ is a radical of the formula --CO--NH--A¹, --NH--CO--A¹,--NH--CO--OA¹ or --NH--CO--NA¹ A², where A¹ and A² are eachindependently of the other C₁ -C₈ -alkyl, 2-cyanoethyl, benzyl, C₁ -C₄-alkanoyloxy-C₂ -C₄ -alkyl, C₁ -C₄ -alkoxycarbonyl-C₁ -C₄ -alkyl, C₁ -C₄-alkoxycarbonyloxy-C₂ -C₄ -alkyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl,or else --NA¹ A² is amino,

Z¹ is hydrogen, methyl, methoxy or the radical --NHCOZ⁷ or --NHCO ₂ Z⁷where Z⁷ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which may beinterrupted by 1 oxygen atom in ether function,

Z³ is hydrogen, C₁ -C₈ -alkyl, 2-cyanoethyl, benzyl, C₁ -C₄-alkanoyloxy-C₂ -C₄ -alkyl, C₁ -C₄ -alkoxycarbonyl-C₁ -C₄ -alkyl or C₁-C₄ -alkoxycarbonyloxy-C₂ -C₄ -alkyl.

Very particular emphasis for use as mixture components is given topyridone dyes of the formula IVa or IVb where L¹⁰ is the radical--NH--COA¹, where A¹ is C₁ -C₈ -alkyl, which may be interrupted by 1oxygen atom in ether function, and Z¹ is the radical --NH--COZ⁷ or--NHCO₂ Z⁷, where Z⁷ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, whichmay be interrupted by 1 oxygen atom in ether function.

Preference for use as mixture components is further given to dyes of theformula V where

L¹¹ is chlorine

L¹² is hydrogen or methyl,

L¹³ is hydrogen, and

L² is a radical of the formula IXa, IXc, IXe, IXf or IXg, emphasis beinggiven to those dyes in which Z¹ is hydrogen or the radical --NH--COZ⁷ or--NHCO₂ Z⁷, where Z⁷ is in each case as defined above.

Particular preference for use as mixture components is given to dyes ofthe formula V where

L¹¹ is chlorine,

L¹² is hydrogen or methyl,

L¹³ is hydrogen, and

L² is a radical of the formula IXa or IXc where

Z¹ is hydrogen, methyl or acetylamino,

Z² is hydrogen or methoxy, and

Z³ are each independently of the other hydrogen, benzyl or substitutedor unsubstituted C₁ -C₈ -alkyl.

Preferred mixture components also include anthraquinone dyes of theformula VI, VII and/or VIII where

R¹, R² and R³ are each independently of the others alkyl or alkoxyalkyl,which may each have up to 15 carbon atoms and can be substituted byphenyl, C₁ -C₄ -alkyl or C₁ -C₄ -alkoxyphenyl and interrupted by 1 or 2oxygen atoms in ether function.

Emphasis for use as mixture components is also given to anthraquinonedyes of the formula VIa ##STR10## where a is 0 or 1,

R¹ is C₁ -C₁₅ -alkyl,

R² is C₁ -C₁₅ -alkyl, a radical of the formula

    [--E.sup.1 --O].sub.p --R.sup.7,

where

E¹ is C₂ -C₄ -alkylene,

p is 1, 2, 3 or 4, and

R⁷ is C₁ -C₄ -alkyl or phenyl, or else, when a is 0, hydrogen, and

R³ is C₁ -C₁₅ -alkyl or unsubstituted or C₁ -C₁₅ -alkyl- or C₁ -C₁₅-alkoxy-substituted phenyl.

Particularly preferred mixture components also include anthraquinonedyes of the formula VIb ##STR11## where a is 0 or 1,

R² is C₁ -C₁₅ -alkyl, a radical of the formula

    [--E.sup.1 --O].sub.p --R.sup.7,

where

E¹ is C₂ -C₄ -alkylene,

p is 1, 2, 3 or 4, and

R⁷ is C₁ -C₄ -alkyl or phenyl, or else, when a is 0, hydrogen, and

R⁸ is C₁ -C₁₅ -alkyl or C₁ -C₁₅ -alkoxy.

Particularly preferred mixture components also include anthraquinonedyes of the formula IVc ##STR12## where R² is C₁ -C₁₅ -alkyl or aradical of the formula

    [--E.sup.1 --O].sub.p --R.sup.7,

where

E¹ R⁷ and p are each as defined above, and

R¹ and R³ are each independently of the other hydrogen or unsubstitutedor C₁ -C₁₅ -alkyl- or C₁ -C₁₅ -alkoxy-substituted benzyl or phenyl, C₄-C₁₅ -alkanoyloxyalkyl, C₄ -C₁₅ -alkoxycarbonyloxyalkyl, C₄ -C₁₅-alkoxycarbonylalkyl or the radical R₂.

Emphasis is given to dye mixtures comprising an anthraquinone dye of theformula VI and a dye of the formula I.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VI and a dye of the formula II.

Emphasis as further given to dye mixtures comprising an anthraquinonedye of the formula VI and a dye of the formula III.

Emphasis as further given to dye mixtures comprising an anthraquinonedye of the formula VI and a dye of the formula IV.

Emphasis as further given to dye mixtures comprising an anthraquinonedye of the formula VI and a dye of the formula V.

Emphasis as further given to dye mixtures comprising an anthraquinonedye of the formula VII and a dye of the formula I.

Emphasis as further given to dye mixtures comprising an anthraquinonedye of the formula VII and a dye of the formula II.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VII and a dye of the formula III.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VII and a dye of the formula IV.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VII and a dye of the formula V.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VIII and a dye of the formula I.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VIII and a dye of the formula II.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VIII and a dye of the formula III.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VIII and a dye of the formula IV.

Emphasis is further given to dye mixtures comprising an anthraquinonedye of the formula VIII and a dye of the formula V.

Of particular suitability are dye mixtures comprising an anthraquinonedye of the formula VI or VII, of which those dye mixtures comprising ananthraquinone dye of the formula VI are particularly important.

Also of particular suitability are dye mixtures comprising a dye of theformula I.

Of very particular importance are those dye mixtures that comprise ananthraquinone dye of the formula VI and a dye of the formula I.

The dye mixtures of the invention generally contain from 10 to 90% byweight, preferably from 40 to 80% by weight, in particular from 70 to80% by weight, each percentage being based on the weight of the dyemixture, of one or more anthraquinone dyes and also from 10 to 90% byweight, preferably from 20 to 60% by weight, in particular from 20 to30% by weight, each percentage being based on the weight of the dyemixture, of one or more dyes of the formula I, II, III, IV and/or V.

The novel dye mixtures can be obtained in a conventional manner, forexample by mixing the individual dyes in the abovementioned weightratio.

The anthraquinone dyes are known per se and described for example inEP-A-337 200, EP-A-351 968 and EP-A-480 278 or can be obtained by themethods mentioned therein.

The dyes of the formula I, II, III, IV and V are likewise known anddescribed for example in U.S. Pat. No. 5,079,365, earlier PatentApplication PCT/EP/92/00505 also in EP-A-480 252 and EP-A-479 068.

The cyan dye mixtures of the invention are notable for advantageousapplication properties. They show high solubility in the color ribbon(high compatibility with the binder), high stability in the printingink, good transferability, high image stability (ie. good light fastnessand also good stability to ambient influences, for example humidity,temperature or chemicals) and permit flexible coloristic adaptation togiven subtractive primary inks in yellow and magenta to achieve anoptimal trichromatic system (maximum brilliance of primary or mixedcolors and a deep neutral black).

Of particular noteworthiness is the spectrally uniform decay rate of theindividual components on irradiation, ie. the dye which has the inferiorlight-fastness as an individual dye does not decay preferentially.

The present invention also provides a process for transferring dyes froma transfer to plastic-coated paper by diffusion or sublimation by meansof an energy source, which comprises using a transfer on which there isa dye mixture as defined at the beginning.

The dye transfers required for the process of the invention are preparedas follows. The dye mixtures are incorporated in a suitable organicsolvent or in mixtures of solvents with one or more binders and with orwithout assistants to form a printing ink. It preferably contains thedye mixture in a molecularly dispersed, ie. dissolved, form. Theprinting ink can then be knife coated onto an inert substrate and airdried. Suitable organic solvents for the dye mixtures are for examplethose in which the solubility of the dye mixtures at 20° C. is greaterthan 1% by weight, preferably greater than 5% by weight.

Examples are ethanol, propanol, isobutanol, tetrahydrofuran, methylenechloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene,chlorobenzene and mixtures thereof.

As binders it is possible to use any resin or polymer material that issoluble in organic solvents and capable of binding the dye mixture tothe inert substrate in such a way that it will not rub off. Preferenceis here given to those binders which, after the air drying of theprinting ink, hold the dye mixture in the form of a clear, transparentfilm in which no visible crystallization of the dye mixture will occur.

Binders of this type are mentioned for example in EP-A-441 282 and inpatent applications cited therein. Other possibilities are saturatedlinear polyesters.

Preferred binders are ethylcellulose, ethylhydroxyethylcellulose,polyvinyl butyrate, polyvinyl acetate, cellulose propionate andsaturated linear polyesters.

The weight ratio of a binder to dye mixture is in general within therange from 1:1 to 10:1.

Suitable assistants are for example release agents as mentioned in saidEP-A-441 282 and patent applications cited therein. It is also possibleto use in particular organic additives which prevent crystallization ofthe transfer dyes in the course of storage or on heating of the colorribbon, for example cholesterol or vanillin.

Suitable inert substrates are described for example in said EP andpatent applications cited therein. The thickness of the substrate is ingeneral from 3 to 30 μm, preferably from 5 to 10 μm.

The dye receptor layer can be basically any thermally stable plasticlayer that possesses affinity for the dyes to be transferred, forexample modified polycarbonates or polyesters. Further details may befound for example in said EP and patent applications cited therein.

The transfer is effected by means of an energy source, for example bymeans of a laser or by means of a thermal head that must be heatable to≦300° C. in order for dye transfer to take place within the time ranget: 0 >t>15 msec. In the course of transfer, the dye migrates out of thetransfer sheet and diffuses into the surface coating of the receivingmedium.

The dye mixtures of the invention are also advantageous for dyeingsynthetic materials, for example polyesters, polyamides orpolycarbonates. Of particular suitability are textile fabrics made ofpolyester or polyamide or polyester-cotton blend fabrics.

The novel dye mixtures are also advantageous for preparing color filtersas described for example in EP-A-399 473.

Finally, they can also be used with advantage as colorants for preparingtoners for electrophotography.

Embodiments of the invention will now be more particularly described byway of example.

EXAMPLES

Table 1 below lists the individual dyes used as mixture components.

                                      TABLE 1                                     __________________________________________________________________________    Dye No.                                                                            Structure                                                                __________________________________________________________________________          ##STR13##                                                               2                                                                                   ##STR14##                                                               3                                                                                   ##STR15##                                                               4                                                                                   ##STR16##                                                               5                                                                                   ##STR17##                                                               6                                                                                   ##STR18##                                                               7                                                                                   ##STR19##                                                               8                                                                                   ##STR20##                                                               9                                                                                   ##STR21##                                                               10                                                                                  ##STR22##                                                               11                                                                                  ##STR23##                                                               12                                                                                  ##STR24##                                                               13                                                                                  ##STR25##                                                               14                                                                                  ##STR26##                                                               15                                                                                  ##STR27##                                                               16                                                                                  ##STR28##                                                               17                                                                                  ##STR29##                                                               18                                                                                  ##STR30##                                                               19                                                                                  ##STR31##                                                               20                                                                                  ##STR32##                                                               21                                                                                  ##STR33##                                                               22                                                                                  ##STR34##                                                               23                                                                                  ##STR35##                                                               24                                                                                  ##STR36##                                                               25                                                                                  ##STR37##                                                               26                                                                                  ##STR38##                                                               27                                                                                  ##STR39##                                                               28                                                                                  ##STR40##                                                               29                                                                                  ##STR41##                                                               30                                                                                  ##STR42##                                                               31                                                                                  ##STR43##                                                               32                                                                                  ##STR44##                                                               33                                                                                  ##STR45##                                                               34                                                                                  ##STR46##                                                               35                                                                                  ##STR47##                                                               36                                                                                  ##STR48##                                                               37                                                                                  ##STR49##                                                               __________________________________________________________________________

Table 2 below lists the light fastness (LF) of the individual dyes 1 to31 and their thermal stability (TS). The value reported here andhereinafter as a measure of the light fastness is the number of hours ofirradiation after which 20% of the dye quantity originally present hadbeen destroyed.

The thermal stability is determined by storing the prints in a dryingcabinet at 70° C. for 1 week. It is assessed on a scale from 1 to 6,where 1 denotes very good and 6 inadequate.

                  TABLE 2                                                         ______________________________________                                        Dye No.         LF      TS                                                    ______________________________________                                        1               86      1                                                     2               46      3                                                     3               a)      a)                                                    4               a)      a)                                                    5               61       2+                                                   6                6      2                                                     7               a)      a)                                                    8               a)      a)                                                    9               <20     3                                                     10              a)      a)                                                    11              16       2+                                                   12              a)      a)                                                    13              40      3                                                     14              a)      a)                                                    15              a)      a)                                                    16              90      3                                                     17              29      2                                                     18              a)      a)                                                    19              14      1                                                     20              85       3+                                                   21              24      1                                                     22              168     1                                                     23              96      1                                                     24              31      3                                                     25              37      2                                                     26              70                                                            27              80      1                                                     28              238     2                                                     29              285     1                                                     30              190     1                                                     31              215     1                                                     32              20      3                                                     33              81      3                                                     34              27      1                                                     35              104     1                                                     36              86      1                                                     37               7      1                                                     ______________________________________                                         a) No values were ascertainable, since the dye was either completely          insoluble or only very sparingly soluble and thus crystallized out in the     color ribbon.                                                            

a) No values were ascertainable, since the dye was either completelyinsoluble or only very sparingly soluble and thus crystallized out inthe color ribbon.

General method:

a) 10 g of dye mixture are stirred with or without brief heating to80°-90° C. into 100 g of a 10% strength by weight solution of a binder(Vylon.sup.• 290 from Toyobo) in 4.5:2:2 v/v/v methyl ethyl ketone/toluene/cyclohexanone.

The printing ink is applied with a 6 μm doctor to a polyester film 6 μmin thickness whose back has been coated with a suitable lubricatinglayer and is blown dry with a hair dryer in the course of 1 minute.Before the color ribbon is used for printing, it subsequently has to airdry for at least 24 hours, since residual solvent can impair theprinting process.

b) The color ribbons are printed in a computer controlled experimentalsetup equipped with a commercial thermal printing head onto Hitachi VY-SVideo Print Paper.

The energy emitted by the thermal printing head is controlled by varyingvoltage with a pulse duration setting of 7 ms and only one pulse beingemitted. The emitted energy is within the range from 0.7 to 2.0 mJ/dot.

Since the degree of coloration is directly proportional to the energysupplied, it is possible to produce a color wedge and analyse itspectroscopically.

The plot of the depth of shade versus the energy supplied per heatingelement is used to determine the Q* value (=energy in mJ for theabsorbance value 1) and the slope m in 1/mJ.

The results obtained are listed below in Table 3, which additionallyshows the mixing ratio (MR--weight ratio), the light fastness and thethermal stability.

                  TABLE 3                                                         ______________________________________                                        Mixture of                                                                    dyes       MR      LF     TS      Q*   m*                                     ______________________________________                                        1/2        3:1     179    1       1.27 1.54                                   1/3        3:1     162     2+     1.15 2.07                                   1/4        3:1     162    1       1.35 1.41                                   1/5        4:1     115    1       1.17 1.71                                   1/6        3:1     132    1       1.41 1.36                                   1/7        2:1     129    1       1.29 1.48                                   1/8        4:1     124    1       1.26 1.56                                   1/9        2:1     120    1       1.41 1.32                                   1/10       2:1     111    1       1.30 1.56                                   1/11       2.5:1   105    1       1.22 1.71                                   1/12       3:1     90     1       1.42 1.40                                   1/13       3.5:1   86      2+     1.25 1.57                                   1/14       1:1     84     1       1.49 1.16                                   1/15       2.5:1   82     1       1.38 1.33                                   1/16       4:1     89     2       1.17 1.60                                   1/17       4:1     77     1       1.11 1.82                                   1/18       2:1     66     1       1.41 1.25                                   1/19       2:1     60     1       1.43 1.38                                   1/20       4:1     60     1       1.48 1.29                                   1/33       1:1     130    1       1.16 1.79                                   1/37       1:1     115    1       0.96 2.83                                   21/6       5:1     41     1       1.04 2.03                                   22/11      5:1     188    1       1.11 2.22                                   23/11      4:1     155    1       1.15 1.57                                   23/7       4:1     115            1.19 1.50                                   23/10      3.1     108    1       1.33 1.27                                   23/26      3:1     95             1.17 1.52                                   23/37      1:1     76     1       0.93 2.54                                   23/24      1:1     81             1.09 1.89                                   23/17      2:1     71             1.18 1.44                                   23/6       5:1     62             1.12 1.65                                   23/25      6:1     58             1.10 1.75                                   27/11      4:1     47     1       1.54 1.10                                   27/20      5:1     47     2       1.46 1.20                                   28/20      4:1     156    2       1.20 1.57                                   28/11      5:1     151    1       1.11 1.93                                   28/24      1.5:1   111     3+     1.26 1.41                                   28/16      5.5:1   110     3+     1.09 1.87                                   29/11      4:1     62     1       1.18 1.48                                   29/16      4:1     59     3       1.00 1.85                                   30/7       6:1     187    2       1.23 1.53                                   30/11      1.5:1   80     1       1.05 1.98                                   30/17      2:1     52                                                         31/7       3:1     191    1       1.17 1.59                                   31/11      4:1     191    1       1.09 1.81                                   31/16      3:1     129            1.15 1.67                                   31/6       5:1     92     1       1.17 1.57                                   31/26      2:1     88             1.12 1.66                                   31/25      6:1     66             1.13 1.74                                   31/24      1:1     64             1.14 1.64                                   31/10      3:1     64             1.43 1.08                                   31/17      2:1     57             1.06 1.96                                   34/33      1:1     80     2       1.08 1.66                                   35/7       1:1     130            1.17 1.85                                   35/11      1:1     74     1       1.15 1.86                                   35/32      1:1     101    2       1.74 0.87                                   ______________________________________                                    

On the assumption that under the action of light the dyes decayindependently of one another and exponentially with time the followingLF values were calculated for mixtures 1/2, 1/6 and 1/13:58, 12.5 and55.

We claim:
 1. Dye mixture comprising at least one anthraquinone dye whoseabsorption maximum is at a wavelength of from 600 to 750 nm and also atleast one dye of the formula I, II, III, IV and/or V ##STR50## where L¹is C₁ -C₂₀ -alkyl, which may be substituted and may be interrupted byfrom 1 to 4 oxygen atoms in ether function, substituted or unsubstitutedphenyl or hydroxyl,L² is a 5- or 6-membered carbocyclic or heterocyclicradical, L³ is cyano, carbamoyl, carboxyl or C₁ -C₄ -alkoxycarbonyl, L⁴is oxygen or a radical of the formula ##STR51## ##STR52## where Q¹ is ineach case C₁ -C₈ -alkyl, which may be interrupted by 1 or 2 oxygen atomsin ether function, L⁵ is hydrogen or C₁ -C₄ -alkyl, L⁶ and L⁷ areidentical or different and each is independently of the other hydrogen,substituted or unsubstituted C₁ -C₁₂ -alkyl, C₅ -C₇ -cycloalkyl,substituted or unsubstituted phenyl, substituted or unsubstituted0pyridyl, substituted or unsubstituted C₁ -C₁₂ -alkanoyl, C₁ -C₁₂-alkoxycarbonyl, substituted or unsubstituted C₁ -C₁₂ -alkylsulfonyl, C₅-C₇ -cycloalkylsulfonyl, substituted or unsubstituted phenylsulfonyl,substituted or unsubstituted pyridylsulfonyl, substituted orunsubstituted benzoyl, pyridylcarbonyl or thienylcarbonyl, or togetherwith the nitrogen atom joining them together are unsubstituted or C₁ -C₄-alkyl-substituted succinimido, unsubstituted or C₁ -C₄-alkyl-substituted phthalimido or a five- or six-membered saturatedheterocyclic radical, which may contain further hetero atoms, is cyanoor a radical of the formula CO--Q², CO--OQ² or CO--NHQ², where Q₂ ishydrogen, C₁ -C₈ -alkyl, which may be substituted and may be interruptedby 1 or 2 oxygen atoms in ether function, C₅ -C₇ -cycloalkyl, phenyl ortolyl, L⁸ is hydrogen, fluorine, chlorine, methyl or a radical of theformula --NH--CO--A¹, --NH--CO--OA¹, --NH--CO--NA¹ A², --NH--CS--OA¹,--NH--CS--NA¹ A², --NH--CO--A³ --NH--SO₂ --A¹, --NH--SO₂ A³ or --NH--SO₂--NA¹ A², where A¹ and A² are identical or different and each isindependently of the other C₁ -C₈ -alkyl, which may be substituted andmay be interrupted by 1 or 2 oxygen atoms in ether function, C₅ -C₇-cycloalkyl, phenyl or tolyl, or else --NA¹ SA² is amino, and A³ is afive- or six-membered aromatic heterocyclic radical, which may bebenzofused and contain one or more hetero atoms selected from the groupconsisting of nitrogen, oxygen and sulfur, L⁹ is hydrogen, fluorine orchlorine, or L⁸ and L⁹ together with the carbon atoms to which they areattached are a five- or six-membered aromatic carbocyclic orheterocyclic ring, L¹⁰ is the abovementioned radical A³ or a radical ofthe formula --CO--OA¹, --CO--NH--A¹, --CO--NH--CO--A¹, --CO--NH--CO--A³,--CO--NH--SO₂ --A³, --NH--CO--A¹, --NH--CO--OA¹, --NH--CO--NA¹ A²,--NH--CS--OA¹, --NH--CS--NA¹ A², --NH--CO--A³, --NH--SO₂ --A¹, --NH--SO₂--A³ or --NH--SO₂ --NA¹ A², where A¹, A² and A³ are each as definedabove, L¹¹ is fluorine, chlorine or bromine, L¹² is hydrogen or C₁ -C₄-alkyl, and L¹³ is hydrogen, fluorine, chlorine or bromine.
 2. Dyemixtures as claimed in claim 1 comprising at least one anthraquinone dyeof the formula VI, VII and/or VIII ##STR53## where a is 0 or 1,R¹, R²and R³ are identical or different and each is independently of theothers hydrogen, alkyl, alkoxyalkyl, alkanoyloxyalkyl,alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, each of which may have upto 20 carbon atoms and be phenyl-, C₁ -C₄ -alkylphenyl-, C₁ -C₄-alkoxyphenyl-, halophenyl-, benzyloxy-, C₁ -C₄ -alkylbenzyloxy-, C₁ -C₄-alkoxybenzyloxy-, halobenzyloxy-, halogen-, hydroxyl- orcyano-substituted, unsubstituted or C₁ -C₁₅ -alkyl-, C₁ -C₁₅ -alkoxy-,halogen- or benzyloxy-substituted phenyl, unsubstituted or C₁ -C₁₅-alkyl-, C₁ -C₁₅ -alkoxy-, halogen- or benzyloxy-substituted cyclohexylor a radical of the formula

    [--E--O]m--R.sup.5,

where E is C₂ -C₆ -alkylene, R⁵ is 1, 2, 3, 4, 5 or 6, and is C₁ -C₄-alkyl or unsubstituted or C₁ -C₄ -alkyl or C₁ -C₄ -alkoxy-substitutedphenyl, and R⁴ is hydrogen or cyano,with the proviso that R² is hydrogenonly when a is
 0. 3. Dye mixtures as claimed in claim 1 comprising from10 to 90% by weight, based on the weight of the dye mixture, of one ormore anthraquinone dyes and also from 10% to 90% by weight, based on theweight of the dye mixture, of one or more dyes of the formula I, II,III, IV and/or V.